The reports of “Chinese pigs in a river” have been percolating over the last two months as the carcasses of the dead farm animals — along with those of bloated ducks and even some swans — have been littering the waterways of China. Nobody knows what is killing the pigs. In a nation that loves its pork, the pig population is about 700 million. But they are dying, and farmers are dumping them in rivers out of fear of government enforcement of laws against unsanitary conditions; by hiding the numbers of dead pigs, farmers may avoid fines.

Last weekend, a new, lethal strain of bird flu, H7N9, was officially identified as the cause of death of two residents of Shanghai, where dead pigs had been spotted floating in a river that supplies about 22 percent of the city’s water. The possibility that the pigs may have passed on the virus has put the global health community on high alert. That’s appropriate, even if the links are unsubstantiated for now. After all, there are times when it’s useful to keep calm and carry on. This is not one of them. A little panic may be useful.

China’s official explanations for the dead pigs have been unconvincing, including blaming a virus that is deadly only in young swine. That wouldn’t explain the dead ducks and swans. Some government officials suggested that the deaths may be due to the country’s filthy rivers, turning China’s dismal environmental record into its best defense.

China has no dearth of health problems. Statistics released this week based on a report from the British medical journal The Lancet attributed 1.2 million premature deaths in China to air pollution. In scientific terms, it is called “ambient particulate matter pollution.” In practical terms, it is responsible for stealing 25 million years of life from China’s present population.

But today’s scare is not just a matter of concern for China. The nation’s insular government, dense population, and environmental ills have already combined to create several global pandemics. The 2003 SARS outbreak began in China, and, by its end, killed about 800 people and caused close to $50 billion in economic losses. China had originally prevented disclosure of the SARS outbreak, telling nervous global public health officials to take a hike.

So, it is no wonder that this week began a flurry of speculation that the H7N9 strain, identified by China’s National Health and Family Planning Commission, was somehow related to the pig deaths. Global health experts, like the Pulitzer Prize-winning author Laurie Garrett, may be predisposed to think in terms of pandemics. But they may also be right: Scientists are already starting to document links between the pig deaths and those of humans. The title of Garrett’s piece in foreignpolicy.com says it all: “Is This a Pandemic Being Born?”

Never before has this strain of avian flu been found in humans, and one of the three known human victims, a man named Wu, is a butcher. While there is also no evidence of human-to-human transmission, the virus has a high mutational potential. Since no one has any confidence in what the Chinese are saying about the dead animals, there should be a healthy dose of skepticism toward the country’s benign explanations for this new virus. The stakes are potentially enormous: The 2009 H1N1 swine flu that killed nearly 300,000 people originated as a mix of bird, swine, and human flu viruses.

World Health Organization doctors are monitoring associates of the victims. Hong Kong is already on a health alert. Maintaining political pressure and public education, even if it based on scientific uncertainties, will protect citizens in every corner of the world. It is important that every nation put pressure on China and demand better explanations and fuller access. It is simply not acceptable that the victims fell ill in early March, just as a new Chinese government was taking office, but officials let three weeks go by before announcing the causes of death.

In fighting a potential pandemic, three weeks can make for a lot of lost time.

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